SlideShare a Scribd company logo
Effects of stimulated Ultraviolet Radiation on the
growth of Maize Seedlings
Keywords:
UV radiation, Zea mays, Chlorophyll concentration, Growth Parameters.
ABSTRACT:
The effects of ultraviolet-A and ultraviolet-B radiation on the growth of maize
seedlings have been studied under controlled conditions. Maize (Zea mays) seeds
were planted and exposed to ultraviolet-A and ultraviolet-B radiation for 0-10 hours.
The results showed a decrease in the concentration of chlorophyll a and b for both
ultraviolet A and B as time of exposure increases. There is also a decrease in the
height, diameter of stem, and number of leaves in the seedlings exposed to UV-A and
UV-B with the increase in the time of exposure. The decrease in chlorophyll a and b
concentrations was more pronounced in plants exposed to UV-B. The study indicates
that UV radiation pose a serious threat to plants and this might lead to significant loss
of production or reduced quality of products in agricultural sectors.
098-103 | JRPS | 2012 | Vol 1 | No 2
This article is governed by the Creative Commons Attribution License (http://creativecommons.org/
licenses/by/2.0), which gives permission for unrestricted use, non-commercial, distribution, and
reproduction in all medium, provided the original work is properly cited.
www.plantsciences.info
Journal of Research in
Plant Sciences
An International Scientific
Research Journal
Authors:
Marius Hedimbi1
,
Natalia Naikaku1
and
Shyam Singh2
.
Institution:
1. Department of Biological
Sciences, University of
Namibia, P/Bag 13301,
Windhoek, Namibia.
2. Department of Physics,
University of Namibia,
P/Bag 13301, Windhoek,
Namibia.
Corresponding author:
Marius Hedimbi.
Email:
mhedimbi@unam.na/
mhedimbi@yahoo.com.
Phone No:
(+264) (61) 206 3425.
Fax :
(+264) (61) 206 3791.
Web Address:
http://plantsciences.info/
documents/PS0020.pdf.
Dates:
Received: 27 Jan 2012 Accepted: 08 Feb 2012 Published: 16 Jun 2012
Article Citation:
Marius Hedimbi, Natalia Naikaku and Shyam Singh.
Effects of stimulated Ultraviolet Radiation on the growth of Maize Seedlings.
Journal of Research in Plant Sciences (2012) 1(2): 098-103
Original Research
Journal of Research in Plant Sciences
JournalofResearchinPlantSciences An International Scientific Research Journal
INTRODUCTION
Ozone depletion has caused an increase in the
amount of ultraviolet-A and ultraviolet-B radiation
reaching the earth’s surface. UV-A has a Wavelength
with a range of 320-440 nm and UV-B has a wavelength
with a range of of 280-320nm. Since it has a shorter
wavelength, UV-B is the most damaging ultraviolet
radiation. The negative effects of UV-A and UV-B on
the growth of maize seedlings have been reported by
Singh et al., (1998), Singh (2000), and Van Kent and
Singh (2008). Numerous investigations have
demonstrated that the effect of UVB radiation
enhancement on plants includes reduction in grain yield,
alteration in species competition, susceptibility to
diseases and changes in plant structure and pigmentation
(Gao et al., 2004). UV-B radiation causes mutations in
plants by promoting the formation of cyclobutane
pyrimidine dimmers between adjacent pyrimidine bases
(Britt 1996).
Maize is one of the most important staple foods
in the world. Therefore the study of maize seedlings to
stimulated UV-A and UV-B light under laboratory
conditions is very important for assessment of the
responses of maize plants to this stress factors in the
field. This may be used to get an overview of what
happens when maize plants are growing in UV regions
under field conditions, and help in finding measures to
protect crops from increasing levels of UV-B and UV-A
radiations.
The objective of this study was to evaluate the
effects of UV radiation on the growth of maize seedlings.
The study evaluated the effects of UV-A and UV-B
radiation on the concentration of chlorophyll a and b in
maize leaves and whether the time of exposure to UV
light has a negative effect on the growth of maize
seedling.
MATERIALS AND METHODS
Growing maize
Fifteen pots were filled with sandy soil. The
depth of the seeds in the soil was kept at 1 cm and the
pots were left to stand under normal light during the day
and under a dark mode during night time by switching
the lights off. Each pot contained three seeds. The pots
were watered with 100ml of water every 3rd
day for two
weeks. The seedlings were divided into two groups. The
first group was used for the determination of chlorophyll
concentration, and the second group was used for health
parameter measurements. Each group was further
subdivided into three groups. One group was exposed to
normal light, another group was exposed to UV-A
(Philips, F40T, 12/B1, Actinic) and another group was
exposed to UV-B (Philips, TL. 40W/12RS, J2) lamb
lights. The exposure was done for 0-10 hours. Each
experiment was done using three replicates.
Extraction of chlorophyll a and b
Eight grams of fresh maize leaves were crushed
using mortar and pestle and mixed with eight milliliters
of 80% acetone. The mixture was left to stand for 20
minutes in the dark and the mixture was then filtered.
The solid particles were discarded and the residue
containing chlorophyll a and b was then transferred to
cuvettes and absorbance was measured with a
spectrophotometer. 80% acetone was used to serve as a
control, which was used to reset the spectrophotometer to
zero before reading the absorbance of the samples
(treatments). Absorbance of chlorophyll a was measured
at wavelength of 645nm and that of chlorophyll b was
measured at a wavelength of 663nm. The number of
chlorophyll was calculated using a modified formula that
was reported by Dere et al., (1998): Chlorophyll a (mg/g
leaf)=[(12.7×A663)-(2.6×A645)] and Chlorophyll b (mg/g
leaf)=[(22.9×A645)–(4.68×A663)].
Measurements of the health parameters
Parameters such as, the width of leaves, height of
the seedling, diameter of stem and dry mass of the plant
Hedimbi et al., 2012
099 Journal of Research in Plant Sciences (2012) 1(2): 098-103
were measured. The width and height were measured
using a ruler while the diameter was measured using a
vernier calliper. The dry mass was determined by putting
fresh seedlings in an oven at 90ºC for 48 hours or until
all the water has evaporated from the seedlings. All
measurements were done using three replicates.
Data Analysis:
A t-test was carried out to test the significance in
differences between means. The tests were done at
confidence interval of 95% and means were considered
to be significantly different when p<0.05.
RESULTS
Chlorophyll concentrations
There was a decrease in the number of
chlorophyll a and chlorophyll b in both in UVA and
UVB as the time of exposure increased (Figure 1). The
level of chlorophyll b was higher (p<0.05) than
Chlorophyll a after exposure to UV radiation.
Furthermore, the level of both chlorophyll a and b were
significantly lower (p<0.05) in seedlings exposed to
UV-B than those exposed to UV-A. There was a
significant decrease in the level of chlorophyll b
(p<0.05) as the time of exposure to both types of UV
radiation increased while there was no significant
difference (p>0.05) in the level of chlorophyll a as the
time of exposure to both types of UV radiation increased
(Figure 1).
Direct effect of UV radiation on the growth of maize
seedlings.
The results showed that the width of leaves,
diameter of the stem and height of the seedling decrease
as the time of exposure both to UV-A and UV-B
increases compared to the control that was not exposed,
whose parameters were higher (Table 1). The decrease in
health parameters appears to be more pronounced with
increased exposure to UV-B and less pronounced with
increased exposure to UV-A (Table 1). There was a
decrease in dry mass of maize seedlings with increase in
exposure to both UV-A and UV-B radiations (Figure 2).
There was no difference (p>0.05) in the dry mass of
plants exposed to UV-A and UV-B at 0, 6 and 8 hours of
exposure to UV radiation (Figure 2).
DISCUSSION
The chlorophyll concentration has been
decreasing as the time of exposure to UV-A and UV-B
radiation has been increasing. It has also been found that
there was more chlorophyll in the leaves exposed to
UV-A than the leaves exposed to UV-B (p<0.05).
Chlorophyll is the green pigment that is found in the
Hedimbi et al., 2012
Journal of Research in Plant Sciences (2012) 1(2): 098-103 100
Figure 2: Percentage (%) dry mass of maize
seedlings after exposure to UV-A and UV-B
radiation for 0-10 hours. Means ± Standard errors of
three replicates are presented.
Figure 1. Concentration of chlorophyll a and b in
maize seedling leaves after exposure to UV-A and
UV-B for 0-10 hours. Means ± Standard errors of
three replicates are presented.
leaves of plants which absorbs sunlight from the
environment and uses its energy to synthesis
carbohydrates from carbon dioxide and water. A
decrease in chlorophyll content in plants is therefore
likely to lead the plant to become more susceptible to
diseases and poisoning by inorganic pollutants such as
arsenic. Britto et al., (2011) reported that uptake of
arsenic by plants plays an important role in transfer of
this toxic element into the food chain. Additionally
inorganic arsenic species are phytotoxic and the elevated
concentration of arsenic in the soil causes a significant
reduction in crop yield (Meharg, 2004, Britto et al.,
2011).
The reduction in health status of plant due to
ultraviolet radiation may cause increased uptake of heavy
metals by the plant (Upadhyaya et al., 2011). Heavy
metal ions, such as copper, play essential roles in many
physiological processes of plants. In trace amounts,
several of these ions are required for metabolism,
growth, and development (Upadhyaya et al., 2011).
However, problems arise when cells are confronted with
an excess of these vital ions or with non-nutritional ions
that lead to cellular damage (Tewari et al., 2006, Zhang
et al., 2008, Panda, 2008, Britto et al., 2011). Heavy
metal toxicity comprises inactivation of biomolecules by
either blocking essential functional groups or by
displacement of essential metal ions (Upadhyaya et al.
2011). In addition, auto-oxidation of redox-active heavy
metals and production of Reactive Oxygen Species
(ROS) by the Fenton reaction causes cellular injury
(Cobbett, 2003, Choudhury and Panda, 2005, Azevedo
and Azevedo, 2006, Upadhyaya et al., 2011).
In the parameters that were measured, the same
trend of a decrease in the parameters measured for both
UV-A and UV-B as the time of exposure increases were
found. The number of leaves of the seedlings where
found to be decreasing as the time of exposure increased
and it was also found that there were more leaves in the
seedlings that were exposed to UV-A than the ones that
were exposed to UV-B radiation. These finding could be
supported by the damage of the chlorophyll caused by
the UV-B. If most of the chlorophyll has been damaged,
there will be reduced absorption of the light for the
seedling to carry out photosynthesis. Therefore the
exposed plant will not grow as unexposed plant, leading
to decrease of the number of leaves in the exposed
seedlings. A reduction in leaves is likely to lead to high
production of stress proteins in plants in response to
increased exposure to UV radiation. Proteins which are
regulated by stress conditions (stress proteins) have been
observed in response to high and low temperatures,
salinity, droughts, and several other stress factors (Pareek
et al., 1997; De Britto et al., 2011).
Singh et al., (1998) did a fluorescence study of
maize irradiated by UV-A. The effects of UV-A on the
growth of maize (Zea mays) plants were investigated by
growing them under two different controlled conditions.
It was found that the growth of the plant was reduced
under UV-A treatment at an early age. A clear-cut
reduction in the growth of the plants was also observed
Hedimbi et al., 2012
101 Journal of Research in Plant Sciences (2012) 1(2): 098-103
Table 1. Effects of UV-A and UV-B on the growth of maize seedlings.
Means ± Standard errors of three replicates are presented.
Width of leaves (cm) Stem diameter (cm) Height of the plant (cm)
Exposure time (h) UV-A UV-B UV-A UV-B UV-A UV-B
0 (control) 1.7±0.1 1.7±0.1 0.4±0.1 0.4±0.1 41 ±1.8 41 ±1.8
2 1.3±0.0 1.2±0.0 0.3±0.0 0.2±0.1 35.5±4.1 27.7±5.8
4 1.3±0.1 1.1±0.0 0.3±0.2 0.2±0.1 30.8±4.7 26.3±3.2
6 1.2±0.1 0.4±0.4 0.2±0.0 0.2±0.0 25.7±4.9 20.7±2.2
8 1.1±0.2 0.4±0.4 0.2±0.1 0.2±0.0 23.2±3.4 18.7±1.9
10 0.7±0.2 0.0±0.0 0.1±0.0 0.1±0.0 19.3±0.6 12 ±0.6
Hedimbi et al., 2012
Journal of Research in Plant Sciences (2012) 1(2): 098-103 102
by Singh et al., (1998). Gao et al., (2004) carried out a
field experiment to study the effects of supplementary
Ultraviolet- B Irradiance on Maize Yield and qualities.
The field studies on UV-B radiation effect on plants have
been recommended to use the UV and
Photo-synthetically Active Radiation (PAR) irradiance
provided by natural light. The study by Gao et al., (2004)
reported the growth and yield responses of maize crop
exposed to enhanced UV-B radiation and the UV-B
effects on the seed qualities under field conditions.
Enhanced UV-B radiation caused a significant reduction
in the dry matter accumulation and the maize yield in
turn was affected. With an increased radiation, the
flavonoid accumulation in maize leaves increased and
the content of chlorophyll a and b of maize leaves were
reduced. The levels of proteins, sugar and starch of
maize seed decreased with enhanced UV-B radiation,
whereas the level of lysine increased with enhanced
UV-B radiation (Gao et al., 2004).
CONCLUSIONS
The study found that both UV-A and UV-B
radiations have a negative effect on chlorophyll content
and health parameter of maize seedlings. Such a decline
in health parameters of maize plants can lead to high
reduction in crop production, reduced grain yield and
increased susceptibility to diseases. With increase in
climate change, the devastating effect of ultraviolet
radiation on crops is likely to become more pronounced.
It is therefore important that farmers develop early
adaptation measures to mitigate crop losses due to
various factors of climate change. Development of maize
strains which are more tolerant to UV radiation damage
needs to be undertaken. The role of central governments
in launching awareness campaigns to educate farmers on
measures to be undertaken to protect their crops also
needs to be accelerated.
REFERENCES
Azevedo JA and Azevedo RA. 2006. Heavy metals and
oxidative stress: where do we go from here? Commn
Biometry Crop Sci., 1(2):135-138.
Britt AB. 1996. DNA damage and repair in plants. Ann.
Rev. Plant, (47):75-100.
Britto R, Mary SR, Sebastian SR and Dharmar K.
2011. Toxic effect of arsenic on ten rice varieties. J Res
Plant Sci., 1:007-012.
Choudhury S and Panda SK. 2005. Role of salicylic
acid in regulating cadmium induced oxidative stress in
Oryza sativa L roots. Bulg. J. Plant Physiol., 30(3-4):95-
110.
Cobbet CS, Hussain D and Haydon MJ. 2003.
Structural and functional relationships between type 1B
heavy metal transporting P-type ATPases in Arabidopsis.
New Phytol,, 159:315-321.
Dere S, Gunes T and Sivaci R. 1998.
Spectrophotometric determination of chlorophyll –A, B
and total carotenoid contents of some algae species using
different solvents. Tr J Botany, 22:13-17.
Gao W, Zeng Y, Slusser JR, Heisle GM, Grant RH,
Xu J and He D. 2004. Effects of supplementary
Ultraviolet-B radiance on maize yields and qualities.
Photochem. Photobio., 80:127-131.
Meharg AA. 2004. Arsenic in rice: understanding a new
disaster for South-East Asia. Trends Plant Sci.,
9:415-417.
Panda SK. 2008. Impact of copper on reactive oxygen
species, lipid peroxidation and antioxidants in Lemna
minor. Biol Plant., 52(3):561-564.
Pareek A, Singla SL and Grover A. 1997. In strategies
for improvement salt tolerance in higher plants (Jaiwal
PK, Singh RB & Gulati A,eds). Oxford and IBH, New
Hedimbi et al., 2012
103 Journal of Research in Plant Sciences (2012) 1(2): 098-103
Delhi. 365-391.
Singh S, Dube A and Gupta PK. 1998. Fluorescence
study of maize irradiated by UV-A. Pure App Opt.,
7:39-42.
Singh S. 2000. Effects of UV-B on the growth of maize
plants using fluorescence parameters. Asian J Physics.,
9:861.
Tewari RK, Kumar P and Sharma PN. 2006.
Antioxidant responses to enhanced generation of
superoxide anion radical and hydrogen peroxide in the
copper-stressed mulberry plants. Planta 223:1145-1153.
Upadhyaya H, Bhattacharjee MK, Deboshree R,
Soumitra S. 2011. Toxic effect of copper on ten rice
cultivars. J Res Plant Sci., 1:038-044.
Van Kent AA and Singh S. 2008. Effects of UV-A and
UV-B radiation on vegetation. Atti Della Fondazione
Giogio Ronchi, 58(3):687-715.
Zhang H, Xia Y, Wang G and Shen Z. 2008. Excess
copper induces accumulation of hydrogen peroxide and
increases lipid peroxidation and total activity of
copper–zinc superoxide dismutase in roots of Elsholtzia
haichowensis. Planta 227:465-475.
Submit your articles online at www.plantsciences.info
Advantages
Easy online submission
Complete Peer review
Affordable Charges
Quick processing
Extensive indexing
You retain your copyright
submit@plantsciences.info
www.plantsciences.info/Submit.php.

More Related Content

What's hot

Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
Adarsh Patel
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
SoraxRoxas
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
abhimad1306
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
Kirthika Elangovan
 
Radioactivity
RadioactivityRadioactivity
Radioactivity
Dr. Tanuja Nautiyal
 
Radiation pollution
Radiation pollutionRadiation pollution
Radiation pollution
ponrajan
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
Maryam Saddiqa
 
Radiation pollution
Radiation pollutionRadiation pollution
Radiation pollution
Rahul Kamble
 
Radioactive waste and their impact on aquatic organisms
Radioactive waste and their impact on aquatic organismsRadioactive waste and their impact on aquatic organisms
Radioactive waste and their impact on aquatic organisms
Chamara Prabhath
 
Nuclear hazards and human health
Nuclear hazards and human health  Nuclear hazards and human health
Nuclear hazards and human health
Dr. Naveen Gaurav srivastava
 
Nuclear hazard
Nuclear hazardNuclear hazard
Nuclear hazard
Haritha Dharmadas
 
Nuclear hazard
Nuclear hazardNuclear hazard
Nuclear hazard
Harsh Mishra
 
Nuclear pollution
Nuclear pollutionNuclear pollution
Nuclear pollution
suru_yadav
 
Real radiation pollution
Real radiation pollutionReal radiation pollution
Real radiation pollution
Ivy Lontoc Capistrano
 
Radioactive+thermal pollution
Radioactive+thermal pollutionRadioactive+thermal pollution
Radioactive+thermal pollution
Muhahammad Zeeshan Ali
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
naveenagirish
 
Nuclear Pollution And Genetics
Nuclear Pollution And GeneticsNuclear Pollution And Genetics
Nuclear Pollution And Genetics
mehrangaiz
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
ManabSharma1
 
Chernobyl disaster and Radioactive waste
Chernobyl disaster and Radioactive waste Chernobyl disaster and Radioactive waste
Chernobyl disaster and Radioactive waste
Dheeraj Gava
 
Nuclear energy and radiation pollution
Nuclear energy and radiation pollutionNuclear energy and radiation pollution
Nuclear energy and radiation pollution
Chandrani Goswami
 

What's hot (20)

Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Radioactivity
RadioactivityRadioactivity
Radioactivity
 
Radiation pollution
Radiation pollutionRadiation pollution
Radiation pollution
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Radiation pollution
Radiation pollutionRadiation pollution
Radiation pollution
 
Radioactive waste and their impact on aquatic organisms
Radioactive waste and their impact on aquatic organismsRadioactive waste and their impact on aquatic organisms
Radioactive waste and their impact on aquatic organisms
 
Nuclear hazards and human health
Nuclear hazards and human health  Nuclear hazards and human health
Nuclear hazards and human health
 
Nuclear hazard
Nuclear hazardNuclear hazard
Nuclear hazard
 
Nuclear hazard
Nuclear hazardNuclear hazard
Nuclear hazard
 
Nuclear pollution
Nuclear pollutionNuclear pollution
Nuclear pollution
 
Real radiation pollution
Real radiation pollutionReal radiation pollution
Real radiation pollution
 
Radioactive+thermal pollution
Radioactive+thermal pollutionRadioactive+thermal pollution
Radioactive+thermal pollution
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Nuclear Pollution And Genetics
Nuclear Pollution And GeneticsNuclear Pollution And Genetics
Nuclear Pollution And Genetics
 
Radioactive pollution
Radioactive pollutionRadioactive pollution
Radioactive pollution
 
Chernobyl disaster and Radioactive waste
Chernobyl disaster and Radioactive waste Chernobyl disaster and Radioactive waste
Chernobyl disaster and Radioactive waste
 
Nuclear energy and radiation pollution
Nuclear energy and radiation pollutionNuclear energy and radiation pollution
Nuclear energy and radiation pollution
 

Similar to Effects of stimulated Ultraviolet Radiation on the growth of Maize Seedlings

Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...
Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...
Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...
Agriculture Journal IJOEAR
 
Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...
Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...
Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...
Professor Bashir Omolaran Bello
 
surender credit seminar.ppt silver nanoparticles
surender credit seminar.ppt silver nanoparticlessurender credit seminar.ppt silver nanoparticles
surender credit seminar.ppt silver nanoparticles
SurenderKumar488475
 
Determining gamma radiation dose......Leonard
Determining gamma radiation dose......LeonardDetermining gamma radiation dose......Leonard
Determining gamma radiation dose......Leonard
Lenard Chilembo
 
U04507118124
U04507118124U04507118124
U04507118124
IJERA Editor
 
Impact of photosynthesis on crop yield
Impact of photosynthesis on crop yieldImpact of photosynthesis on crop yield
Impact of photosynthesis on crop yield
ANWAR225MD
 
C047012020
C047012020C047012020
C047012020
inventy
 
Benefits Over Traditional Wired Sensing Technology
Benefits Over Traditional Wired Sensing TechnologyBenefits Over Traditional Wired Sensing Technology
Benefits Over Traditional Wired Sensing Technology
Christina Valadez
 
Inhibitory effect of camphor leaf powder on germination and growth of the wee...
Inhibitory effect of camphor leaf powder on germination and growth of the wee...Inhibitory effect of camphor leaf powder on germination and growth of the wee...
Inhibitory effect of camphor leaf powder on germination and growth of the wee...
Ibrahem Aboueldarag
 
INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...
INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...
INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...
Ibrahem Aboueldarag
 
Applications Of Radioisotopes In Agriculture
Applications Of Radioisotopes In AgricultureApplications Of Radioisotopes In Agriculture
Applications Of Radioisotopes In Agriculture
Daniel Wachtel
 
49.Antitumour and Radioprotective activity of Alloe vera
49.Antitumour and Radioprotective activity of Alloe vera49.Antitumour and Radioprotective activity of Alloe vera
49.Antitumour and Radioprotective activity of Alloe vera
Annadurai B
 
Antifungal activity of Silver/ Silicon dioxide Nanocomposites
Antifungal activity of Silver/ Silicon dioxide NanocompositesAntifungal activity of Silver/ Silicon dioxide Nanocomposites
Antifungal activity of Silver/ Silicon dioxide Nanocomposites
21PCH001JEFINF
 
Potential of silicon fertilization in the resistance of chestnut plants toink...
Potential of silicon fertilization in the resistance of chestnut plants toink...Potential of silicon fertilization in the resistance of chestnut plants toink...
Potential of silicon fertilization in the resistance of chestnut plants toink...
IJEAB
 
MICRONUTRIENT APPLICATION IN TOMATO
MICRONUTRIENT APPLICATION IN TOMATOMICRONUTRIENT APPLICATION IN TOMATO
MICRONUTRIENT APPLICATION IN TOMATO
SANDEEP VARMA VUNNAM
 
Paper id 71201929
Paper id 71201929Paper id 71201929
Paper id 71201929
IJRAT
 
Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...
Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...
Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...
Premier Publishers
 
No 13. foliar feeding of micronutrient mixtures on growth and yield of okra
No 13. foliar feeding of micronutrient mixtures on growth and yield of okraNo 13. foliar feeding of micronutrient mixtures on growth and yield of okra
No 13. foliar feeding of micronutrient mixtures on growth and yield of okra
PARTNER, BADC, World Bank
 
Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...
Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...
Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...
Innspub Net
 
Sj iwmt mzoa==
Sj iwmt mzoa==Sj iwmt mzoa==
Sj iwmt mzoa==
editorijserin
 

Similar to Effects of stimulated Ultraviolet Radiation on the growth of Maize Seedlings (20)

Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...
Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...
Effect of enhanced solar UVB (280-320nm) radiation on secondary pigment synth...
 
Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...
Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...
Mutagenic Effects of Ultraviolet Radiation on Growth and Agronomic Characters...
 
surender credit seminar.ppt silver nanoparticles
surender credit seminar.ppt silver nanoparticlessurender credit seminar.ppt silver nanoparticles
surender credit seminar.ppt silver nanoparticles
 
Determining gamma radiation dose......Leonard
Determining gamma radiation dose......LeonardDetermining gamma radiation dose......Leonard
Determining gamma radiation dose......Leonard
 
U04507118124
U04507118124U04507118124
U04507118124
 
Impact of photosynthesis on crop yield
Impact of photosynthesis on crop yieldImpact of photosynthesis on crop yield
Impact of photosynthesis on crop yield
 
C047012020
C047012020C047012020
C047012020
 
Benefits Over Traditional Wired Sensing Technology
Benefits Over Traditional Wired Sensing TechnologyBenefits Over Traditional Wired Sensing Technology
Benefits Over Traditional Wired Sensing Technology
 
Inhibitory effect of camphor leaf powder on germination and growth of the wee...
Inhibitory effect of camphor leaf powder on germination and growth of the wee...Inhibitory effect of camphor leaf powder on germination and growth of the wee...
Inhibitory effect of camphor leaf powder on germination and growth of the wee...
 
INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...
INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...
INHIBITORY EFFECT OF CAMPHOR LEAF POWDER ON GERMINATION AND GROWTH OF THE WEE...
 
Applications Of Radioisotopes In Agriculture
Applications Of Radioisotopes In AgricultureApplications Of Radioisotopes In Agriculture
Applications Of Radioisotopes In Agriculture
 
49.Antitumour and Radioprotective activity of Alloe vera
49.Antitumour and Radioprotective activity of Alloe vera49.Antitumour and Radioprotective activity of Alloe vera
49.Antitumour and Radioprotective activity of Alloe vera
 
Antifungal activity of Silver/ Silicon dioxide Nanocomposites
Antifungal activity of Silver/ Silicon dioxide NanocompositesAntifungal activity of Silver/ Silicon dioxide Nanocomposites
Antifungal activity of Silver/ Silicon dioxide Nanocomposites
 
Potential of silicon fertilization in the resistance of chestnut plants toink...
Potential of silicon fertilization in the resistance of chestnut plants toink...Potential of silicon fertilization in the resistance of chestnut plants toink...
Potential of silicon fertilization in the resistance of chestnut plants toink...
 
MICRONUTRIENT APPLICATION IN TOMATO
MICRONUTRIENT APPLICATION IN TOMATOMICRONUTRIENT APPLICATION IN TOMATO
MICRONUTRIENT APPLICATION IN TOMATO
 
Paper id 71201929
Paper id 71201929Paper id 71201929
Paper id 71201929
 
Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...
Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...
Effects of β-cyclodextrin on in vitro rooting and bulbing of lilium (Lilium l...
 
No 13. foliar feeding of micronutrient mixtures on growth and yield of okra
No 13. foliar feeding of micronutrient mixtures on growth and yield of okraNo 13. foliar feeding of micronutrient mixtures on growth and yield of okra
No 13. foliar feeding of micronutrient mixtures on growth and yield of okra
 
Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...
Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...
Effects of 60Co gamma radiation doses on seed germination of Jatropha curcas ...
 
Sj iwmt mzoa==
Sj iwmt mzoa==Sj iwmt mzoa==
Sj iwmt mzoa==
 

More from researchplantsciences

Effect of some pre sowing treatments on Sapindus laurifolius seed germination
Effect of some pre sowing treatments on Sapindus laurifolius seed germinationEffect of some pre sowing treatments on Sapindus laurifolius seed germination
Effect of some pre sowing treatments on Sapindus laurifolius seed germination
researchplantsciences
 
Preliminary phytochemical studies and evaluation of Antipyretic property of t...
Preliminary phytochemical studies and evaluation of Antipyretic property of t...Preliminary phytochemical studies and evaluation of Antipyretic property of t...
Preliminary phytochemical studies and evaluation of Antipyretic property of t...
researchplantsciences
 
Karyomorphological studies in two species of Allium L.
Karyomorphological studies in two species of Allium L.Karyomorphological studies in two species of Allium L.
Karyomorphological studies in two species of Allium L.
researchplantsciences
 
Comparison of some physiological parameters in leaves and stems of wild and c...
Comparison of some physiological parameters in leaves and stems of wild and c...Comparison of some physiological parameters in leaves and stems of wild and c...
Comparison of some physiological parameters in leaves and stems of wild and c...
researchplantsciences
 
Quantification of total phenolics and flavonoids and evaluation of in vitro a...
Quantification of total phenolics and flavonoids and evaluation of in vitro a...Quantification of total phenolics and flavonoids and evaluation of in vitro a...
Quantification of total phenolics and flavonoids and evaluation of in vitro a...
researchplantsciences
 
Bioadsorbent to clean industrial effluents by seaweeds
Bioadsorbent to clean industrial effluents by seaweedsBioadsorbent to clean industrial effluents by seaweeds
Bioadsorbent to clean industrial effluents by seaweeds
researchplantsciences
 
Nodal anatomical study of certain members of the Rutaceae
Nodal anatomical study of certain members of the RutaceaeNodal anatomical study of certain members of the Rutaceae
Nodal anatomical study of certain members of the Rutaceae
researchplantsciences
 
The identity and occurrence of primula reidii duthie var. reidii from Shivali...
The identity and occurrence of primula reidii duthie var. reidii from Shivali...The identity and occurrence of primula reidii duthie var. reidii from Shivali...
The identity and occurrence of primula reidii duthie var. reidii from Shivali...
researchplantsciences
 
Plants used for basketry in kasaragod district, kerala
Plants used for basketry in kasaragod district, keralaPlants used for basketry in kasaragod district, kerala
Plants used for basketry in kasaragod district, kerala
researchplantsciences
 
Phytochemical investigation of tropical medicinal plants - Stereospermum cola...
Phytochemical investigation of tropical medicinal plants - Stereospermum cola...Phytochemical investigation of tropical medicinal plants - Stereospermum cola...
Phytochemical investigation of tropical medicinal plants - Stereospermum cola...
researchplantsciences
 
Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...
Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...
Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...
researchplantsciences
 
Formation, growth and productivity of the tea bush
Formation, growth and productivity of the tea bushFormation, growth and productivity of the tea bush
Formation, growth and productivity of the tea bush
researchplantsciences
 
The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...
The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...
The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...
researchplantsciences
 
Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...
Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...
Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...
researchplantsciences
 
Toxic effect of copper on ten rice cultivars
Toxic effect of copper on ten rice cultivars Toxic effect of copper on ten rice cultivars
Toxic effect of copper on ten rice cultivars
researchplantsciences
 
Phytochemical studies on selected medicinal plant Gymnema sylvestre.
Phytochemical studies on selected medicinal plant Gymnema sylvestre.Phytochemical studies on selected medicinal plant Gymnema sylvestre.
Phytochemical studies on selected medicinal plant Gymnema sylvestre.
researchplantsciences
 
Phytochemical analysis of eight medicinal plants of Lamiaceae
Phytochemical analysis of eight medicinal plants of LamiaceaePhytochemical analysis of eight medicinal plants of Lamiaceae
Phytochemical analysis of eight medicinal plants of Lamiaceae
researchplantsciences
 
Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...
Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...
Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...
researchplantsciences
 
Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...
Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...
Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...
researchplantsciences
 
Influence of provenance in seed and emergence characteristics of a gigantic l...
Influence of provenance in seed and emergence characteristics of a gigantic l...Influence of provenance in seed and emergence characteristics of a gigantic l...
Influence of provenance in seed and emergence characteristics of a gigantic l...
researchplantsciences
 

More from researchplantsciences (20)

Effect of some pre sowing treatments on Sapindus laurifolius seed germination
Effect of some pre sowing treatments on Sapindus laurifolius seed germinationEffect of some pre sowing treatments on Sapindus laurifolius seed germination
Effect of some pre sowing treatments on Sapindus laurifolius seed germination
 
Preliminary phytochemical studies and evaluation of Antipyretic property of t...
Preliminary phytochemical studies and evaluation of Antipyretic property of t...Preliminary phytochemical studies and evaluation of Antipyretic property of t...
Preliminary phytochemical studies and evaluation of Antipyretic property of t...
 
Karyomorphological studies in two species of Allium L.
Karyomorphological studies in two species of Allium L.Karyomorphological studies in two species of Allium L.
Karyomorphological studies in two species of Allium L.
 
Comparison of some physiological parameters in leaves and stems of wild and c...
Comparison of some physiological parameters in leaves and stems of wild and c...Comparison of some physiological parameters in leaves and stems of wild and c...
Comparison of some physiological parameters in leaves and stems of wild and c...
 
Quantification of total phenolics and flavonoids and evaluation of in vitro a...
Quantification of total phenolics and flavonoids and evaluation of in vitro a...Quantification of total phenolics and flavonoids and evaluation of in vitro a...
Quantification of total phenolics and flavonoids and evaluation of in vitro a...
 
Bioadsorbent to clean industrial effluents by seaweeds
Bioadsorbent to clean industrial effluents by seaweedsBioadsorbent to clean industrial effluents by seaweeds
Bioadsorbent to clean industrial effluents by seaweeds
 
Nodal anatomical study of certain members of the Rutaceae
Nodal anatomical study of certain members of the RutaceaeNodal anatomical study of certain members of the Rutaceae
Nodal anatomical study of certain members of the Rutaceae
 
The identity and occurrence of primula reidii duthie var. reidii from Shivali...
The identity and occurrence of primula reidii duthie var. reidii from Shivali...The identity and occurrence of primula reidii duthie var. reidii from Shivali...
The identity and occurrence of primula reidii duthie var. reidii from Shivali...
 
Plants used for basketry in kasaragod district, kerala
Plants used for basketry in kasaragod district, keralaPlants used for basketry in kasaragod district, kerala
Plants used for basketry in kasaragod district, kerala
 
Phytochemical investigation of tropical medicinal plants - Stereospermum cola...
Phytochemical investigation of tropical medicinal plants - Stereospermum cola...Phytochemical investigation of tropical medicinal plants - Stereospermum cola...
Phytochemical investigation of tropical medicinal plants - Stereospermum cola...
 
Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...
Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...
Intraspecific variation in Solanum xanthocarpum schard. and wendl.revealed by...
 
Formation, growth and productivity of the tea bush
Formation, growth and productivity of the tea bushFormation, growth and productivity of the tea bush
Formation, growth and productivity of the tea bush
 
The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...
The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...
The Medicinally important Convolvulacean members used by the Kattunaikkan Tri...
 
Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...
Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...
Effect of Sucrose and Benzyl Adenine in the promotion of cut flower vase life...
 
Toxic effect of copper on ten rice cultivars
Toxic effect of copper on ten rice cultivars Toxic effect of copper on ten rice cultivars
Toxic effect of copper on ten rice cultivars
 
Phytochemical studies on selected medicinal plant Gymnema sylvestre.
Phytochemical studies on selected medicinal plant Gymnema sylvestre.Phytochemical studies on selected medicinal plant Gymnema sylvestre.
Phytochemical studies on selected medicinal plant Gymnema sylvestre.
 
Phytochemical analysis of eight medicinal plants of Lamiaceae
Phytochemical analysis of eight medicinal plants of LamiaceaePhytochemical analysis of eight medicinal plants of Lamiaceae
Phytochemical analysis of eight medicinal plants of Lamiaceae
 
Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...
Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...
Maruthamalai hills of Western Ghats, Coimbatore District, Tamil Nadu - A pote...
 
Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...
Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...
Ipomoea capitellata var. multilobata (Convolvulaceae) – A new variety from Ja...
 
Influence of provenance in seed and emergence characteristics of a gigantic l...
Influence of provenance in seed and emergence characteristics of a gigantic l...Influence of provenance in seed and emergence characteristics of a gigantic l...
Influence of provenance in seed and emergence characteristics of a gigantic l...
 

Effects of stimulated Ultraviolet Radiation on the growth of Maize Seedlings

  • 1. Effects of stimulated Ultraviolet Radiation on the growth of Maize Seedlings Keywords: UV radiation, Zea mays, Chlorophyll concentration, Growth Parameters. ABSTRACT: The effects of ultraviolet-A and ultraviolet-B radiation on the growth of maize seedlings have been studied under controlled conditions. Maize (Zea mays) seeds were planted and exposed to ultraviolet-A and ultraviolet-B radiation for 0-10 hours. The results showed a decrease in the concentration of chlorophyll a and b for both ultraviolet A and B as time of exposure increases. There is also a decrease in the height, diameter of stem, and number of leaves in the seedlings exposed to UV-A and UV-B with the increase in the time of exposure. The decrease in chlorophyll a and b concentrations was more pronounced in plants exposed to UV-B. The study indicates that UV radiation pose a serious threat to plants and this might lead to significant loss of production or reduced quality of products in agricultural sectors. 098-103 | JRPS | 2012 | Vol 1 | No 2 This article is governed by the Creative Commons Attribution License (http://creativecommons.org/ licenses/by/2.0), which gives permission for unrestricted use, non-commercial, distribution, and reproduction in all medium, provided the original work is properly cited. www.plantsciences.info Journal of Research in Plant Sciences An International Scientific Research Journal Authors: Marius Hedimbi1 , Natalia Naikaku1 and Shyam Singh2 . Institution: 1. Department of Biological Sciences, University of Namibia, P/Bag 13301, Windhoek, Namibia. 2. Department of Physics, University of Namibia, P/Bag 13301, Windhoek, Namibia. Corresponding author: Marius Hedimbi. Email: mhedimbi@unam.na/ mhedimbi@yahoo.com. Phone No: (+264) (61) 206 3425. Fax : (+264) (61) 206 3791. Web Address: http://plantsciences.info/ documents/PS0020.pdf. Dates: Received: 27 Jan 2012 Accepted: 08 Feb 2012 Published: 16 Jun 2012 Article Citation: Marius Hedimbi, Natalia Naikaku and Shyam Singh. Effects of stimulated Ultraviolet Radiation on the growth of Maize Seedlings. Journal of Research in Plant Sciences (2012) 1(2): 098-103 Original Research Journal of Research in Plant Sciences JournalofResearchinPlantSciences An International Scientific Research Journal
  • 2. INTRODUCTION Ozone depletion has caused an increase in the amount of ultraviolet-A and ultraviolet-B radiation reaching the earth’s surface. UV-A has a Wavelength with a range of 320-440 nm and UV-B has a wavelength with a range of of 280-320nm. Since it has a shorter wavelength, UV-B is the most damaging ultraviolet radiation. The negative effects of UV-A and UV-B on the growth of maize seedlings have been reported by Singh et al., (1998), Singh (2000), and Van Kent and Singh (2008). Numerous investigations have demonstrated that the effect of UVB radiation enhancement on plants includes reduction in grain yield, alteration in species competition, susceptibility to diseases and changes in plant structure and pigmentation (Gao et al., 2004). UV-B radiation causes mutations in plants by promoting the formation of cyclobutane pyrimidine dimmers between adjacent pyrimidine bases (Britt 1996). Maize is one of the most important staple foods in the world. Therefore the study of maize seedlings to stimulated UV-A and UV-B light under laboratory conditions is very important for assessment of the responses of maize plants to this stress factors in the field. This may be used to get an overview of what happens when maize plants are growing in UV regions under field conditions, and help in finding measures to protect crops from increasing levels of UV-B and UV-A radiations. The objective of this study was to evaluate the effects of UV radiation on the growth of maize seedlings. The study evaluated the effects of UV-A and UV-B radiation on the concentration of chlorophyll a and b in maize leaves and whether the time of exposure to UV light has a negative effect on the growth of maize seedling. MATERIALS AND METHODS Growing maize Fifteen pots were filled with sandy soil. The depth of the seeds in the soil was kept at 1 cm and the pots were left to stand under normal light during the day and under a dark mode during night time by switching the lights off. Each pot contained three seeds. The pots were watered with 100ml of water every 3rd day for two weeks. The seedlings were divided into two groups. The first group was used for the determination of chlorophyll concentration, and the second group was used for health parameter measurements. Each group was further subdivided into three groups. One group was exposed to normal light, another group was exposed to UV-A (Philips, F40T, 12/B1, Actinic) and another group was exposed to UV-B (Philips, TL. 40W/12RS, J2) lamb lights. The exposure was done for 0-10 hours. Each experiment was done using three replicates. Extraction of chlorophyll a and b Eight grams of fresh maize leaves were crushed using mortar and pestle and mixed with eight milliliters of 80% acetone. The mixture was left to stand for 20 minutes in the dark and the mixture was then filtered. The solid particles were discarded and the residue containing chlorophyll a and b was then transferred to cuvettes and absorbance was measured with a spectrophotometer. 80% acetone was used to serve as a control, which was used to reset the spectrophotometer to zero before reading the absorbance of the samples (treatments). Absorbance of chlorophyll a was measured at wavelength of 645nm and that of chlorophyll b was measured at a wavelength of 663nm. The number of chlorophyll was calculated using a modified formula that was reported by Dere et al., (1998): Chlorophyll a (mg/g leaf)=[(12.7×A663)-(2.6×A645)] and Chlorophyll b (mg/g leaf)=[(22.9×A645)–(4.68×A663)]. Measurements of the health parameters Parameters such as, the width of leaves, height of the seedling, diameter of stem and dry mass of the plant Hedimbi et al., 2012 099 Journal of Research in Plant Sciences (2012) 1(2): 098-103
  • 3. were measured. The width and height were measured using a ruler while the diameter was measured using a vernier calliper. The dry mass was determined by putting fresh seedlings in an oven at 90ºC for 48 hours or until all the water has evaporated from the seedlings. All measurements were done using three replicates. Data Analysis: A t-test was carried out to test the significance in differences between means. The tests were done at confidence interval of 95% and means were considered to be significantly different when p<0.05. RESULTS Chlorophyll concentrations There was a decrease in the number of chlorophyll a and chlorophyll b in both in UVA and UVB as the time of exposure increased (Figure 1). The level of chlorophyll b was higher (p<0.05) than Chlorophyll a after exposure to UV radiation. Furthermore, the level of both chlorophyll a and b were significantly lower (p<0.05) in seedlings exposed to UV-B than those exposed to UV-A. There was a significant decrease in the level of chlorophyll b (p<0.05) as the time of exposure to both types of UV radiation increased while there was no significant difference (p>0.05) in the level of chlorophyll a as the time of exposure to both types of UV radiation increased (Figure 1). Direct effect of UV radiation on the growth of maize seedlings. The results showed that the width of leaves, diameter of the stem and height of the seedling decrease as the time of exposure both to UV-A and UV-B increases compared to the control that was not exposed, whose parameters were higher (Table 1). The decrease in health parameters appears to be more pronounced with increased exposure to UV-B and less pronounced with increased exposure to UV-A (Table 1). There was a decrease in dry mass of maize seedlings with increase in exposure to both UV-A and UV-B radiations (Figure 2). There was no difference (p>0.05) in the dry mass of plants exposed to UV-A and UV-B at 0, 6 and 8 hours of exposure to UV radiation (Figure 2). DISCUSSION The chlorophyll concentration has been decreasing as the time of exposure to UV-A and UV-B radiation has been increasing. It has also been found that there was more chlorophyll in the leaves exposed to UV-A than the leaves exposed to UV-B (p<0.05). Chlorophyll is the green pigment that is found in the Hedimbi et al., 2012 Journal of Research in Plant Sciences (2012) 1(2): 098-103 100 Figure 2: Percentage (%) dry mass of maize seedlings after exposure to UV-A and UV-B radiation for 0-10 hours. Means ± Standard errors of three replicates are presented. Figure 1. Concentration of chlorophyll a and b in maize seedling leaves after exposure to UV-A and UV-B for 0-10 hours. Means ± Standard errors of three replicates are presented.
  • 4. leaves of plants which absorbs sunlight from the environment and uses its energy to synthesis carbohydrates from carbon dioxide and water. A decrease in chlorophyll content in plants is therefore likely to lead the plant to become more susceptible to diseases and poisoning by inorganic pollutants such as arsenic. Britto et al., (2011) reported that uptake of arsenic by plants plays an important role in transfer of this toxic element into the food chain. Additionally inorganic arsenic species are phytotoxic and the elevated concentration of arsenic in the soil causes a significant reduction in crop yield (Meharg, 2004, Britto et al., 2011). The reduction in health status of plant due to ultraviolet radiation may cause increased uptake of heavy metals by the plant (Upadhyaya et al., 2011). Heavy metal ions, such as copper, play essential roles in many physiological processes of plants. In trace amounts, several of these ions are required for metabolism, growth, and development (Upadhyaya et al., 2011). However, problems arise when cells are confronted with an excess of these vital ions or with non-nutritional ions that lead to cellular damage (Tewari et al., 2006, Zhang et al., 2008, Panda, 2008, Britto et al., 2011). Heavy metal toxicity comprises inactivation of biomolecules by either blocking essential functional groups or by displacement of essential metal ions (Upadhyaya et al. 2011). In addition, auto-oxidation of redox-active heavy metals and production of Reactive Oxygen Species (ROS) by the Fenton reaction causes cellular injury (Cobbett, 2003, Choudhury and Panda, 2005, Azevedo and Azevedo, 2006, Upadhyaya et al., 2011). In the parameters that were measured, the same trend of a decrease in the parameters measured for both UV-A and UV-B as the time of exposure increases were found. The number of leaves of the seedlings where found to be decreasing as the time of exposure increased and it was also found that there were more leaves in the seedlings that were exposed to UV-A than the ones that were exposed to UV-B radiation. These finding could be supported by the damage of the chlorophyll caused by the UV-B. If most of the chlorophyll has been damaged, there will be reduced absorption of the light for the seedling to carry out photosynthesis. Therefore the exposed plant will not grow as unexposed plant, leading to decrease of the number of leaves in the exposed seedlings. A reduction in leaves is likely to lead to high production of stress proteins in plants in response to increased exposure to UV radiation. Proteins which are regulated by stress conditions (stress proteins) have been observed in response to high and low temperatures, salinity, droughts, and several other stress factors (Pareek et al., 1997; De Britto et al., 2011). Singh et al., (1998) did a fluorescence study of maize irradiated by UV-A. The effects of UV-A on the growth of maize (Zea mays) plants were investigated by growing them under two different controlled conditions. It was found that the growth of the plant was reduced under UV-A treatment at an early age. A clear-cut reduction in the growth of the plants was also observed Hedimbi et al., 2012 101 Journal of Research in Plant Sciences (2012) 1(2): 098-103 Table 1. Effects of UV-A and UV-B on the growth of maize seedlings. Means ± Standard errors of three replicates are presented. Width of leaves (cm) Stem diameter (cm) Height of the plant (cm) Exposure time (h) UV-A UV-B UV-A UV-B UV-A UV-B 0 (control) 1.7±0.1 1.7±0.1 0.4±0.1 0.4±0.1 41 ±1.8 41 ±1.8 2 1.3±0.0 1.2±0.0 0.3±0.0 0.2±0.1 35.5±4.1 27.7±5.8 4 1.3±0.1 1.1±0.0 0.3±0.2 0.2±0.1 30.8±4.7 26.3±3.2 6 1.2±0.1 0.4±0.4 0.2±0.0 0.2±0.0 25.7±4.9 20.7±2.2 8 1.1±0.2 0.4±0.4 0.2±0.1 0.2±0.0 23.2±3.4 18.7±1.9 10 0.7±0.2 0.0±0.0 0.1±0.0 0.1±0.0 19.3±0.6 12 ±0.6
  • 5. Hedimbi et al., 2012 Journal of Research in Plant Sciences (2012) 1(2): 098-103 102 by Singh et al., (1998). Gao et al., (2004) carried out a field experiment to study the effects of supplementary Ultraviolet- B Irradiance on Maize Yield and qualities. The field studies on UV-B radiation effect on plants have been recommended to use the UV and Photo-synthetically Active Radiation (PAR) irradiance provided by natural light. The study by Gao et al., (2004) reported the growth and yield responses of maize crop exposed to enhanced UV-B radiation and the UV-B effects on the seed qualities under field conditions. Enhanced UV-B radiation caused a significant reduction in the dry matter accumulation and the maize yield in turn was affected. With an increased radiation, the flavonoid accumulation in maize leaves increased and the content of chlorophyll a and b of maize leaves were reduced. The levels of proteins, sugar and starch of maize seed decreased with enhanced UV-B radiation, whereas the level of lysine increased with enhanced UV-B radiation (Gao et al., 2004). CONCLUSIONS The study found that both UV-A and UV-B radiations have a negative effect on chlorophyll content and health parameter of maize seedlings. Such a decline in health parameters of maize plants can lead to high reduction in crop production, reduced grain yield and increased susceptibility to diseases. With increase in climate change, the devastating effect of ultraviolet radiation on crops is likely to become more pronounced. It is therefore important that farmers develop early adaptation measures to mitigate crop losses due to various factors of climate change. Development of maize strains which are more tolerant to UV radiation damage needs to be undertaken. The role of central governments in launching awareness campaigns to educate farmers on measures to be undertaken to protect their crops also needs to be accelerated. REFERENCES Azevedo JA and Azevedo RA. 2006. Heavy metals and oxidative stress: where do we go from here? Commn Biometry Crop Sci., 1(2):135-138. Britt AB. 1996. DNA damage and repair in plants. Ann. Rev. Plant, (47):75-100. Britto R, Mary SR, Sebastian SR and Dharmar K. 2011. Toxic effect of arsenic on ten rice varieties. J Res Plant Sci., 1:007-012. Choudhury S and Panda SK. 2005. Role of salicylic acid in regulating cadmium induced oxidative stress in Oryza sativa L roots. Bulg. J. Plant Physiol., 30(3-4):95- 110. Cobbet CS, Hussain D and Haydon MJ. 2003. Structural and functional relationships between type 1B heavy metal transporting P-type ATPases in Arabidopsis. New Phytol,, 159:315-321. Dere S, Gunes T and Sivaci R. 1998. Spectrophotometric determination of chlorophyll –A, B and total carotenoid contents of some algae species using different solvents. Tr J Botany, 22:13-17. Gao W, Zeng Y, Slusser JR, Heisle GM, Grant RH, Xu J and He D. 2004. Effects of supplementary Ultraviolet-B radiance on maize yields and qualities. Photochem. Photobio., 80:127-131. Meharg AA. 2004. Arsenic in rice: understanding a new disaster for South-East Asia. Trends Plant Sci., 9:415-417. Panda SK. 2008. Impact of copper on reactive oxygen species, lipid peroxidation and antioxidants in Lemna minor. Biol Plant., 52(3):561-564. Pareek A, Singla SL and Grover A. 1997. In strategies for improvement salt tolerance in higher plants (Jaiwal PK, Singh RB & Gulati A,eds). Oxford and IBH, New
  • 6. Hedimbi et al., 2012 103 Journal of Research in Plant Sciences (2012) 1(2): 098-103 Delhi. 365-391. Singh S, Dube A and Gupta PK. 1998. Fluorescence study of maize irradiated by UV-A. Pure App Opt., 7:39-42. Singh S. 2000. Effects of UV-B on the growth of maize plants using fluorescence parameters. Asian J Physics., 9:861. Tewari RK, Kumar P and Sharma PN. 2006. Antioxidant responses to enhanced generation of superoxide anion radical and hydrogen peroxide in the copper-stressed mulberry plants. Planta 223:1145-1153. Upadhyaya H, Bhattacharjee MK, Deboshree R, Soumitra S. 2011. Toxic effect of copper on ten rice cultivars. J Res Plant Sci., 1:038-044. Van Kent AA and Singh S. 2008. Effects of UV-A and UV-B radiation on vegetation. Atti Della Fondazione Giogio Ronchi, 58(3):687-715. Zhang H, Xia Y, Wang G and Shen Z. 2008. Excess copper induces accumulation of hydrogen peroxide and increases lipid peroxidation and total activity of copper–zinc superoxide dismutase in roots of Elsholtzia haichowensis. Planta 227:465-475. Submit your articles online at www.plantsciences.info Advantages Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright submit@plantsciences.info www.plantsciences.info/Submit.php.